The structure of SAICAR synthase: an enzyme in the de novo pathway of purine nucleotide biosynthesis
| Autor: | A. I. Grebenko, V.V. Barynin, Keith S. Wilson, Vladimir M. Levdikov, Victor S. Lamzin, William Melik-Adamyan |
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| Rok vydání: | 1998 |
| Předmět: |
Models
Molecular crystal structure Protein Folding Protein Conformation Molecular Sequence Data Phosphoribosylaminoimidazolesuccinocarboxamide Saccharomyces cerevisiae Crystallography X-Ray Glutathione Synthase Structure-Activity Relationship chemistry.chemical_compound Adenosine Triphosphate Biosynthesis Structural Biology Nucleotide Amino Acid Sequence Peptide Synthases Purine metabolism Molecular Biology Conserved Sequence chemistry.chemical_classification DNA ligase Binding Sites biology ATP synthase purine biosynthesis Sulfates Active site Adenylosuccinate synthase Ribonucleotides Aminoimidazole Carboxamide Cyclic AMP-Dependent Protein Kinases ATP-binding protein chemistry Biochemistry Purines biology.protein phosphoribosylaminoimidazolesuccinocarboxamide (SAICAR) synthase |
| Zdroj: | Structure. 6:363-376 |
| ISSN: | 0969-2126 |
| Popis: | Background: The biosynthesis of key metabolic components is of major interest to biologists. Studies of de novo purine synthesis are aimed at obtaining a deeper understanding of this central pathway and the development of effective chemotherapeutic agents. Phosphoribosylaminoimidazolesuccinocarboxamide (SAICAR) synthase catalyses the seventh step out of ten in the biosynthesis of purine nucleotides. To date, only one structure of an enzyme involved in purine biosynthesis has been reported: adenylosuccinate synthetase, which catalyses the first committed step in the synthesis of AMP from IMP. Results: We report the first three-dimensional structure of a SAICAR synthase, from Saccharomyces cerevisiae . It is a monomer with three domains. The first two domains consist of antiparallel β sheets and the third is composed of two α helices. There is a long deep cleft made up of residues from all three domains. Comparison of SAICAR synthases by alignment of their sequences reveals a number of conserved residues, mostly located in the cleft. The presence of two sulphate ions bound in the cleft, the structure of SAICAR synthase in complex with ATP and a comparison of this structure with that of other ATP-dependent proteins point to the interdomain cleft as the location of the active site. Conclusions: The topology of the first domain of SAICAR synthase resembles that of the N-terminal domain of proteins belonging to the cyclic AMP-dependent protein kinase family. The fold of the second domain is similar to that of members of the D-alanine:D-alanine ligase family. Together these enzymes form a new superfamily of mononucleotide-binding domains. There appears to be no other enzyme, however, which is composed of the same combination of three domains, with the individual topologies found in SAICAR synthase. |
| Databáze: | OpenAIRE |
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